The inherent potential of molecular beam epitaxy (MBE) has been exploited to grow large area slices of low defect density GaAlAs/GaAs heterostructures to fabricate several semiconductor guided wave devices. Passive rib waveguides had losses of<2 dB cm−1. Phase modulators exhibited a π phase shift for an applied bias of 9 V, internal losses of less than 2.5 dB with a modulation capability to l.2 GHz. Directional couplers fabricated from the same material exhibited a switching voltage of 16 volts and an extinction ratio better than 14 dB. The MBE growth procedure is outlined and the steps critical to the subsequent successful fabrication of guided wave devices are discussed.